CVE-2025-37959
A flaw in the Linux kernel allows packets redirected between network namespaces with bpf_redirect_peer to carry hidden state from one namespace to another. This can cause packets to be dropped or misrouted, breaking network connectivity for containers or services. The issue is fixed in newer kernel releases.
An official fix is available, so this entry is kept for 30 days and then removed automatically.
Who is affected
Linux kernel 6.15 and later, including Debian 11.0 systems that use this kernel. It affects users running container runtimes such as Cilium that rely on bpf_redirect_peer for packet routing.
Real-world impact
An attacker could exploit this flaw to disrupt network traffic between containers or namespaces, effectively causing a denial‑of‑service for applications running inside those containers.
Why this severity
The CVSS score of 9.4 reflects that the vulnerability can be triggered over the network without authentication, and it can compromise confidentiality, integrity, and availability of network traffic. The lack of required privileges and user interaction makes it highly dangerous.
What to do about it
- 01Upgrade the Linux kernel to version 6.15 or later.
- 02Reboot the system to load the new kernel.
NVD description
Timeline
- May 20, 2025 · May 20, 2025PublishedDisclosed and added to the National Vulnerability Database.
- Jul 30, 2026 · 7d agoAdvisory updatedThe NVD record was last revised.
- Jul 30, 2026 · 6d agoOfficial fix availableA vendor patch or mitigation now exists — see the remediation steps above.
How it’s attacked
References & advisories
- git.kernel.org/stable/c/355b0526336c0bf2bf…patch
- git.kernel.org/stable/c/9e15ef33ba39fb6d9d…patch
- git.kernel.org/stable/c/b37e54259cab4f78b5…patch
- git.kernel.org/stable/c/c43272299488798142…patch
- git.kernel.org/stable/c/de1067cc8cf0e8c11a…patch
- lists.debian.org/debian-lts-announce/2025/08…third party advisory
- cert-portal.siemens.com/productcert/html/ssa-019113…